Question about Acer Predator Orion – 5000 PO5-615s

That would be the detailed description of the mainboard:

The Intel® Z490 Chipset is a single-chip with proven reliability and performance.
Support one PCI Express x16 slot
Support one PCI Express x1 slot
Two M.2 slots (1 x Key E M.2 2230 slot for WLAN co-lay with PCI-E,USB signal, supports Intel CNVi interface, and 2 x Key M.2 2242/2280 slot for SSD and optane memory, supports PCIe or SATA signal)
Integrated four SATA 6Gb/s host controllers
Two USB 2.0 ports supported
Two USB 3.2 Gen1 ports and two USB 3.2 Gen2 Type-A ports
Two USB 3.2 Gen1 Type-A ports, One USB 3.2 Gen2 Type-A ports and one USB3.2 Gen2 Type-C port
Serial Peripheral Interface (SPI) support
Intel® High Definition Audio Controller

- Is the PC quiet?
Subjective question - this is a gamer PC, here gaming performance is the main focus. In this case, the volume usually plays a less important role. However, the PC does not seem to attract negative attention in this respect.

- Can you install an additional HDD?
Yes, you can.

- Is it easy to install an additional RAM bar?
Yes, it is. You just have to insert it into the slot.